API 5CT

OCTG is short for Oil Country Tubular Goods and refers to the pipes used in oil and gas extraction. The API 5CT standard covers the OCTG coupling, threading, and materials connections used in drilling operations. It includes instructions on dimensions, sizes, wall thicknesses, materials grades, tolerance limits, and performance requirements. The API 5CT is widely used in the oil and gas industry for both onshore and offshore drilling operations. OCTG manufacturers need to adhere to the standards set out in the API 5CT to ensure that their products are compatible with the oil and gas industry’s equipment and operations. By following the API 5CT, manufacturers can be confident that their OCTG products will be able to meet the demands of the oil and gas industry.

Why choose tuspipe for for Your Oil & Gas Needs?

TUSPIPE stands tall as an indispensable ally for the oil and gas industry. Our pipes serve as the very lifelines that efficiently channel vital resources. Understanding the criticality of high-performing pipes in this sector, we engineer our products to withstand the rigorous demands and aggressive environments typical of oil and gas applications. Our pipes are compliant with the stringent API 5CT standards for casing and tubing, ensuring unmatched strength and durability. Additionally, catering to the diverse requirements of the oil and gas sector, TUSPIPE offers a variety of thread types including but not limited to BTC, LTC, STC, and premium threads, which ensure secure and reliable connections. Choose TUSPIPE for pipes that meet the industry’s highest standards, tailored to optimize your operations in the oil and gas sector.

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Steel Grade of API 5CT Standard

Group 1: All casing and tubing in Grades with H, J, K, N and R
Group 2: All casing and tubing in Grades with C, L, M and T
Group 3: All casing and tubing in Grade P
Group 4: All casing in Grade Q

Dimensions and Sizes of API 5CT Casing and Tubing

- Specification & Size of API 5CT Tubing

DN	O. D.		Weight		W. T.		End Processing
	O. D.		Non-upset coupling-thread	Upset coupling-thread	W. T.		Steel Grade
	Inch	mm	lb./ft.	lb./ft.	Inch	mm	H40	J55	L80	N80	C90	T95	P110
2 3/8	2.375	60.32	4	–	0.167	4.24	PU	PN	PN	PN	PN	PN	–
			4.6	4.7	0.19	4.83	PNU	PNU	PNU	PNU	PNU	PNU	PNU
			5.8	5.95	0.254	6.45	–	–	PNU	PNU	PNU	PNU	PNU
			6.6	–	0.295	7.49	–	–	P	–	P	P	–
			7.35	7.45	0.336	8.53	–	–	PU	–	PU	PU	–
2 7/8	2.875	73.02	6.4	6.5	0.217	5.51	PNU	PNU	–	–	–	–	–
			7.8	7.9	0.276	7.01	–	–	–	–	–	–	–
			8.6	8.7	0.308	7.82	–	–	PLB	PLB	PLBE	–	PLB
			9.35	9.45	0.34	8.64	–	–	PLB	PLB	PLBE	–	PLB
			10.5	–	0.392	9.96	–	–	PLB	PLB	PLB	–	PLB
			11.5	–	0.44	11.18	–	–	–	–	PLB	–
3 1/2	3.5	88.9	7.7	–	0.216	5.49	PN	PN	PN	PN	PN	PN	–
			9.2	9.3	0.254	6.45	PNU	PNU	PNU	PNU	PNU	PNU	PNU
			10.2	–	0.289	7.34	PN	PN	PN	PN	PN	PN	–
			12.7	12.95	0.375	9.52	–	–	PNU	PNU	PNU	PNU	PNU
			14.3	–	0.43	10.92	–	–	P	–	P	P	–
			15.5	–	0.476	12.09	–	–	P	–	P	P	–
			17	–	0.53	13.46	–	–	P	–	P	P	–
4	4	101.6	9.5	–	0.226	5.74	PN	PN	PN	PN	PN	PN	–
			–	11	0.262	6.65	PU	PU	PU	PU	PU	PU	–
			13.2	–	0.33	8.38	–	–	P	–	P	P	–
			16.1	–	0.415	10.54	–	–	P	–	P	P	–
			18.9	–	0.5	12.7	–	–	P	–	P	P	–
			22.2	–	0.61	15.49	–	–	P	–	P	P	–
4 1/2	4.5	114.3	12.6	12.75	0.271	6.88	PNU	PNU	PNU	PNU	PNU	PNU	–
			15.2	–	0.337	8.56	–	–	P	–	P	P	–
			17	–	0.38	9.65	–	–	P	–	P	P	–
			18.9	–	0.43	10.92	–	–	P	–	P	P	PLB
			21.5	–	0.5	12.7	–	–	P	–	P	P	PLB
			23.7	–	0.56	14.22	–	–	P	–	P	P	PLB
			26.1	–	0.63	16	–	–	P	–	P	P	PLB
P——Plain；N—— Non-upset coupling-thread；U—— Upset coupling-thread； L——Integral

- Specification & Size of API 5CT Casing

DN	O. D.		Weight		W. T.			End Machining Form
	O. D.		Weight		W. T.			Steel Grade
	Inch	mm	lb/ft	kg/m	Inch	mm	H40	J55	L80	N80	C90	P110
	Inch	mm	lb/ft	kg/m	Inch	mm	H40	K55	L80	N80	T95	P110
4 1/2	4.5	114.3	9.5	14.14	0.205	5.21	PS	PS	–	–	–	–
			10.5	15.63	0.224	5.69	–	PSB	–	–	–	–
			11.6	17.26	0.25	6.35	–	PSLB	PLB	PLB	PLB	PLB
			13.5	20.09	0.29	7.37	–	–	PLB	PLB	PLB	PLB
			15.1	22.47	0.337	9.56	–	–	–	–	–	PLB
5	5	127	11.5	17.11	0.22	5.59	–	PS	–	–	–	–
			13	19.35	0.253	6.43	–	PSLB	–	–	–	–
			15	22.32	0.296	7.52	–	PSLB	PLB	PLB	PLBE	PLB
			18	26.79	0.362	9.19	–	–	PLB	PLB	PLBE	PLB
			21.4	31.85	0.437	11.1	–	–	PLB	PLB	PLB	PLB
			23.2	34.53	0.478	12.14	–	–	–	–	PLB	–
			24.1	35.86	0.5	12.7	–	–	–	–	PLB	–
5 1/2	5.5	139.7	14	20.83	0.244	6.2	PS	PS	–	–	–	–
			15.5	23.07	0.275	6.98	–	PSLB	–	–	–	–
			17	25.3	0.304	7.72	–	PSLB	PLB	PLB	PLBE	PLB
			20	29.76	0.361	9.17	–	–	PLB	PLB	PLBE	PLB
			23	34.23	0.415	10.54	–	–	PLB	PLB	PLBE	PLB
			26.8	39.88	0.5	12.7	–	–	–	–	–	–
			29.7	44.2	0.562	14.27	–	–	–	–	–	–
			32.6	48.51	0.625	15.88	–	–	–	–	–	–
			35.3	52.53	0.687	17.45	–	–	–	–	–	–
			38	56.55	0.75	19.05	–	–	–	–	–	–
			40.5	60.27	0.812	20.62	–	–	–	–	–	–
			43.1	64.14	0.875	22.22	–	–	–	–	–	–
6 5/8	6.625	168.28	20	29.76	0.288	7.32	PS	PSLB	–	–	–	–
			24	35.72	0.352	8.94	–	PSLB	PLB	PLB	PLBE	PLB
			28	41.67	0.417	10.59	–	–	PLB	PLB	PLBE	PLB
			32	47.62	0.475	12.06	–	–	PLB	PLB	PLBE	PLB
7	7	177.8	17	25.3	0.231	5.87	PS	–	–	–	–	–
			20	29.76	0.272	6.91	PS	PS	–	–	–	–
			23	34.23	0.317	8.05	–	PSLB	PLB	PLB	PLBE	–
			26	38.69	0.362	9.19	–	PSLB	PLB	PLB	PLBE	PLB
			29	43.16	0.408	10.36	–	–	PLB	PLB	PLBE	PLB
			32	47.62	0.453	11.51	–	–	PLB	PLB	PLBE	PLB
			35	52.09	0.498	12.65	–	–	PLB	PLB	PLBE	PLB
			38	56.55	0.54	13.72	–	–	PLB	PLB	PLBE	PLB
			42.7	63.54	0.625	15.88	–	–	–	–	–	–
			46.4	69.05	0.687	17.45	–	–	–	–	–	–
			50.1	74.56	0.75	19.05	–	–	–	–	–	–
			53.6	79.77	0.812	20.62	–	–	–	–	–	–
			57.1	84.97	0.875	22.22	–	–	–	–	–	–
7 5/8	7.625	193.68	24	35.72	0.3	7.62	PS	–	–	–	–	–
			26.4	39.29	0.328	8.33	–	PSLB	PLB	PLB	PLBE	PLB
			29.7	44.2	0.375	9.52	–	–	PLB	PLB	PLBE	PLB
			33.7	50.15	0.43	10.92	–	–	PLB	PLB	PLBE	PLB
			39	58.05	0.5	12.7	–	–	PLB	PLB	PLBE	PLB
			42.8	63.69	0.562	14.27	–	–	PLB	PLB	PLB	PLB
			45.3	67.41	0.595	15.11	–	–	PLB	PLB	PLB	PLB
			47.1	70.09	0.625	15.88	–	–	PLB	PLB	PLB	PLB
			51.2	76.19	0.687	17.45	–	–	–	–	–	–
			55.3	80.3	0.75	19.05	–	–	–	–	–	–
8 5/8	8.625	219.08	24	35.72	0.264	6.71	–	PS	–	–	–	–
			28	41.62	0.304	7.72	PS	–	–	–	–	–
			32	47.62	0.352	8.94	PS	PSLB	–	–	–	–
			36	53.57	0.4	10.16	–	PSLB	PLB	PLB	PLBE	PLB
			40	59.53	0.45	11.43	–	–	PLB	PLB	PLBE	PLB
			44	65.48	0.5	12.7	–	–	PLB	PLB	PLBE	PLB
			49	72.92	0.557	14.15	–	–	PLB	PLB	PLBE	PLB
9 5/8	9.625	244.48	32.3	48.07	0.312	7.92	PS	–	–	–	–	–
			36	53.57	0.352	8.94	PS	PSLB	–	–	–	–
			40	59.53	0.395	10.03	–	PSLB	PLB	PLB	PLBE	–
			43.5	64.73	0.435	11.05	–	–	PLB	PLB	PLBE	PLB
			47	69.94	0.472	11.99	–	–	PLB	PLB	PLBE	PLB
			53.5	79.62	0.545	13.84	–	–	PLB	PLB	PLBE	PLB
			58.4	86.91	0.595	15.11	–	–	PLB	PLB	PLB	PLB
			59.4	88.4	0.609	15.47	–	–	–	–	–	–
			64.9	96.58	0.672	17.07	–	–	–	–	–	–
			70.3	104.62	0.734	18.64	–	–	–	–	–	–
			75.6	112.5	0.797	20.24	–	–	–	–	–	–
10 3/4	10.75	273.05	32.75	48.74	0.279	7.09	PS	–	–	–	–	–
			40.5	60.27	0.35	8.89	PS	PSB	–	–	–	–
			15.5	67.71	0.4	10.16	–	PSB	–	–	–	–
			51	75.9	0.45	11.43	–	PSB	PSB	PSB	PSBE	PSB
			55.5	82.59	0.495	12.57	–	–	PSB	PSB	PSBE	PSB
			60.7	90.33	0.545	13.84	–	–	–	–	PSBE	PSB
			65.7	97.77	0.595	15.11	–	–	–	–	PSB	PSB
			73.2	108.93	0.672	17.07	–	–	–	–	–	–
			79.2	117.86	0.734	18.64	–	–	–	–	–	–
			85.3	126.94	0.797	20.24	–	–	–	–	–	–
11 3/4	11.75		42	62.5	0.333	8.46	PS	–	–	–	–	–
			47	69.94	0.375	20.24	–	–	–	–	–	–
			54	80.36	0.435	8.46	–	–	–	–	–	–
			60	89.29	0.489	9.53	–	–	–	–	–	–
			65	96.73	0.534	11.05	–	–	–	–	–	–
			71	105.66	0.582	14.42	–	–	–	–	–	–
13 3/8	13.375	339.73	48	71.43	0.33	8.38	PS	–	–	–	–	–
			54.5	81.1	0.38	9.65	–	PSB	–	–	–	–
			61	90.78	0.43	10.92	–	PSB	–	–	–	–
			68	101.19	0.48	12.19	–	PSB	PSB	PSB	PSB	PSB
			72	107.15	0.514	13.06	–	–	PSB	PSB	PSB	PSB
16	16	406.4	65	96.73	0.375	9.53	PS	–	–	–	–	–
			75	111.61	0.438	11.13	–	PSB	–	–	–	–
			84	125.01	0.495	12.57	–	PSB	–	–	–	–
			109	162.21	0.656	16.66	–	P	P	P	–	P
18 5/8	18.625	473.08	87.5	130.21	0.435	11.05	PS	PSB	–	–	–	–
20	20	508	94	139.89	0.438	11.13	PSL	PSLB	–	–	–	–
			106.5	158.49	0.5	12.7	–	PSLB	–	–	–	–
			133	197.93	0.635	16.13	–	PSLB	–	–	–	–
P——Plain；S——Short-thread；L——Long-thread；B——Buttress thread；E——Extreme thread

Chemical Composition (%) of API 5CT

Chemical Composition of API 5CT，Mass Fraction（%）
Group	Grade	Type	C		Mn		Mo		Cr		Ni	Cu	P	S	Si
Group	Grade	Type	min.	max.	min.	max.	min.	max.	min.	max.	max.	max.	max.	max.	max.
1	H40	—	—	—	—	—	—	—	—	—	—	—	0.03	0.03	—
	J55	—	—	—	—	—	—	—	—	—	—	—	0.03	0.03	—
	K55	—	—	—	—	—	—	—	—	—	—	—	0.03	0.03	—
	N80	1	—	—	—	—	—	—	—	—	—	—	0.03	0.03	—
	N80	Q	—	—	—	—	—	—	—	—	—	—	0.03	0.03	—
	R95	—	—	0.45	—	1.9	—	—	—	—	—	—	0.03	0.03	0.45
2	M65	—	—	—	—	—	—	—	—	—	—	—	0.03	0.03	—
	L80	1	—	0.43	—	1.9	—	—	—	—	0.25	0.35	0.03	0.03	0.45
	L80	9Cr	—	0.15	0.3	0.6	0.9	1.1	8	10	0.5	0.25	0.02	0.01	1
	L81	13Cr	0.15	0.22	0.25	1	—	—	12	14	0.5	0.25	0.02	0.01	1
	C90	1	—	0.35	—	1.2	0.25	0.85	—	1.5	0.99	—	0.02	0.01	—
	T95	1	—	0.35	—	1.2	0.25	0.85	0.4	1.5	0.99	—	0.02	0.01	—
	C110	—	—	0.35	—	1.2	0.25	1	0.4	1.5	0.99	—	0.02	0.005	—
3	P110	—	—	—	—	—	—	—	—	—	—	—	0.03	0.03	—
4	Q125	1	—	0.35	—	1.35	—	0.85	—	1.5	0.99	—	0.02	0.01	—
a. The carbon content for L80 may be increased up to 0, 50 % maximum if the product is oil-quenched.
b. The molybdenum content for Grade C90 Type 1 has no minimum tolerance if the WT is less than 17, 78 mm.
c. The carbon content for R95 may be increased up to 0, 55 % maximum if the product is oil-quenched.
d. The molybdenum content for T95 Type 1 may be decreased to 0, 15 % minimum if the WT is less than 17, 78 mm.
e. For EW Grade P110, the phosphorus content shall be 0,020 % maximum and the sulfur content 0,010 % maximum
NL = no limit. Elements shown shall be reported in product analysis.

Mechanical Properties of API 5CT

Mechanical Properties
Group	Grade	Type	Total	Yield Strength (Mpa)		Tensile	Hardness max
Group	Grade	Type	%	min.	max.	MPa	HRC	HBW
1	H40	—	0.5	276	552	414	—	—
	J55	—	0.5	379	552	517	—	—
	K55	—	0.5	379	552	655	—	—
	N80	1	0.5	552	758	689	—	—
	N80	Q	0.5	552	758	689	—	—
	R95	—	0.5	655	758	724	—	—
2	M65	—	0.5	445	586	586	22	235
	L80	1	0.5	552	655	655	23	241
	L80	9Cr	0.5	552	655	655	23	241
	L81	13Cr	0.5	552	655	655	23	241
	C90	1	0.5	621	724	689	25.4	255
	T95	1	0.5	655	758	724	25.4	255
	C110	—	0.7	758	828	793	30	286
3	P110	—	0.6	758	965	862	—	—
4	Q125	1	0.65	862	1034	931	—	—
a. In case of dispute, laboratory Rockwell C hardness testing shall be used as the referee method.
b. No hardness limits, but the maximum variation is controlled by manufacturer acc API 5CT.

API 5CT Dimensional Deviation

Items		Allowable Deviation
Out Diameter	D ≤ 101.60mm	± 0.79mm
Out Diameter	D ≥ 114.30mm	+ 1.0%, -0.5%
Wall Thickness		-12.50%
Mass (Single Lengths)		+6.5%, -3.5%

Length Range of API 5CT

Length
Item	Scope 1	Scope 2	Scope 3
Tubing	6.10-7.32m	8.53-9.75m	–
Casing	4.88-7.62m	7.62-10.36m	10.36-14.63m

Test and inspection of API 5CT Tubing and Casing

- Hydrostatic Test

Hydrostatic testing is a critical quality control measure during the production of steel pipe. The purpose of the hydrostatic test is to verify that the seam welds and pipe body can withstand the required internal water pressure without leaking. To conduct the test, water is pressurized and injected into the pipe. Once the water pressure reaches the specified level, the pipe is subjected to a thorough examination for leaks. Any leaks that are found are repaired and the hydrostatic test is repeated until the pipe passes inspection. This process ensures that the finished product can safely transport water or other fluids under high pressure without leaking.

- Bend Test

During the production of an API 5CT tubing and casing pipe, a bending test is conducted to ensure the quality of the weld. This test involves taking a sample of the steel pipe and subjecting it to a bending force. The results of the test are then evaluated to determine if there are any cracks in the weld. If no cracks are found, the pipe is deemed to be of acceptable quality. However, if cracks are found, the pipe is rejected and must be repaired or replaced. The bending test is an important part of the production process, as it helps to ensure that the final product is of high quality and will perform as intended.

- Flattening Test

Flattening tests are typically performed during the quality control testing of steel pipes, such as those produced according to the API 5CT specification. The flattening test is used to assess a sample pipe’s resistance to longitudinal deformation (i.e. crack growth) and its ability to maintain its shape under stress. The test is conducted by first welded a ring onto one end of the pipe sample. The other end of the sample is then placed in a jig, which compresses the entire length of the pipe along its longitudinal axis. Once the desired compression is achieved, the jig is released and the sample is removed for inspection. Any cracks or deformations that have occurred during the test are then documented and analyzed. The results of the flattening test can be used to assess the quality of the pipe and its suitability for use in various applications.

- CVN Impact Test

When it comes to tubing and casing pipe production, the impact test is an important quality control measure. Also known as the Charpy test, this test is used to assess a material’s ability to withstand impact. The test involves striking a specimen with a hammer and then measuring the amount of energy that is absorbed. The results are then compared to a standard to determine whether the material meets the required specification. There are three main areas that are tested during impact testing: the pipe body, the weld sea, and the heat-affected zone. By understanding the importance of this test, manufacturers can ensure that their steel pipes meet the required standards for strength and durability.

API 5CT Pipe Ending Processing

- Flat End / Plain End

A plain end, also known as a flat end or square cut, is a type of steel pipe that has a flat end rather than a beveled or threaded end. Plain end pipes are more common in larger diameter pipes and are typically used for carrying fluids under high pressure. One advantage of plain end pipe is that it is easier to weld or connect to other types of pipe. However, plain end pipe is less able to withstand external forces, such as those from wind or waves, and is more susceptible to damage from impacts. As a result, plain end pipe is often used in applications where it will be buried or otherwise protected from the elements.

- Threaded End

Casing is a steel pipe that is used to line the borehole of a drilling well. It is important to use casing in order to prevent collapse of the borehole and to protect the equipment that is being used. Casing is also used to keep out water, gas, and oil from entering the well. The threaded end on a casing pipe is used for making a connection with a screw. This type of connection is known as a threaded joint. In order to make this connection, a casing coupler is used. The coupler is screwed onto the end of the pipe and then the two pipes are connected together with a screw.

- Rounded Nose

A rounded nose on a casing pipe is simply a threaded connection that has been machined to have a rounded, rather than flat, end. This type of connection is often used when space is limited, such as in tight corners or other difficult-to-reach areas. In addition, rounded noses are less likely to snag on surrounding objects, making them ideal for use in high-traffic areas. Although they are more expensive than traditional threaded connections, the increased safety and durability of rounded noses make them well worth the investment.

What is API 5CT OCTG?

Oil country tubular goods (OCTG) is a family of steel pipe products used in the drilling, completion, and production of oil and gas wells. And, API 5CT is the standard for the group of products. OCTG casing and tubing are essential elements in the well construction process, as they provide support and protection for the well bore. Casing is installed first, followed by tubing. The casing is typically made of steel or other strong materials that can withstand the high pressure and temperature of the reservoir. Tubing is also made of steel, but it is thinner walled and carried inside the casing. OCTG products are manufactured to meet specific specifications that are based on the type of well being drilled. For example, sour service casing must be able to resist corrosion from hydrogen sulfide gas. Deepwater casing must be able to withstand the high pressures found at great depths. Ultimately, OCTG products play a vital role in ensuring the safety and efficiency of oil and gas drilling operations.

What is the Difference between API 5CT Casing and Tubing?

API 5CT casing is a tube that is placed in a wellbore in order to protect the wellbore from contamination. Casing is also used to stabilize the wellbore and keep it secure. Drilling and casing operations occur alternately, with the drill string being removed at predetermined intervals. API 5CT tubing is used to carry petroleum from the depths of the well to the surface. Oil and gas may sometimes self-elevate to the surface; however, pumps are typically required in order to bring these fluids to the surface. Tubing typically has a smaller diameter than casing. The main purpose of tubing is to transport petroleum from the well to an external location.